The invention relates to a turn signal control system for a vehicle with turn signal lights attached to both sides of the vehicle, with a manually operated turn signal lever and with a turn signal control unit. The turn signal control unit activates a flashing mode upon deflection of the turn signal lever out of a neutral position into a first deflected position. In the flashing mode the turn signal lights associated with the deflected direction of the lever flash on and off. Furthermore, the turn signal control unit is provided with means for shutting off of the flashing mode.
Passenger vehicles, in particular, are equipped with systems for the shut-off of the turn signals, which mechanically return the turn signal lever to the neutral position, as soon as the steering wheel is returned from the deflected position for operation around a curve to the straight-ahead position. Furthermore, a steering column switch has become known from published German patent application 2728061, published 18 Jan. 1979, in which the flasher return occurs without mechanical contact where reed contacts are released by means of permanent magnets arranged on the steering column. Shut-off systems of this type can lead to a premature or a delayed shut-off of the turn signal in hydraulic steering systems which are frequently applied to agricultural and industrial vehicles and in which no fixed relationship exists between the steering wheel position and driving wheel deflection, and are therefore not always appropriate.
If the shut-off of the turn signal is automatic after a predetermined time interval, this can lead to a premature interruption of the flashing mode if the vehicle is moving slowly, or is waiting, for example, for a traffic light. The application of steering angle sensors to the control of the shut-off is relatively costly and has the disadvantage that the system can respond to steering movements that do not mark the end of the turning process.
A turn signal control system for a motorcycle is described in U.S. Pat. No. 4,972,174, issued 20 Nov. 1990 to Onan, et al. With this control system the turn signals are flashed for a period of time based upon sensed speed. But, this system includes separate left and right turn signal buttons, not a single lever. Also, this system does not include different flashing modes which can be selected depending upon how long an actuator is actuated.